The present invention relates to a power transmission-type gear tester.
Conventional power transmission-type gear testers for testing the bending strength, surface pressure resistance, scoring, etc. of gear teeth are constituted by a pair of driving gears and a pair of test gears, both of which have the same parameters such as tooth number, tooth profile, etc.
However, when test gear modules or their tooth numbers are changed in such gear testers, the driving gears should also be changed to those having the same parameters as those of new test gears. In addition, whenever new gears are tested, the driving gear boxes and test gear boxes should be exchanged to new ones having the sizes corresponding to the new driving gears and test gears. It is apparent that this is economically disadvantageous.
To obviate this disadvantage, Japanese Utility Model Laid-Open No. 64-2139 discloses a power transmission-type gear tester comprising a pair of transmission gear boxes each having a pair of transmission gears for constituting a power-circulating loop, and a pair of test gears provided in the power-circulating loop. Specifically, one transmission gear in each transmission gear box is connected to a torsion bar to which a torque load-applying device is mounted, and another transmission gear in each transmission gear box is connected via a torque detector to a test gear box in which test gears are provided.
In this gear tester, a torque load is applied to the torsion bar in a state where a motor is stopped. After detaching the torque load-applying device from the torsion bar, the motor is operated to carry out the testing of gears. Accordingly, when new gears having different parameters are tested, only the test gears should be changed without changing the transmission gears. In this sense, this gear tester is economically advantageous. In addition, this gear tester can be used for testing small gears.
However, since the testing of gears is conducted in this gear tester in a state where a torque load is applied to the torsion bar in advance, it is impossible to start the test from a state where there is no torque applied to the test gear. Also, the torque load cannot be changed during the continuous operation for testing. Accordingly, to change the torque load, the operation should be stopped.
In addition, in the case of exchanging test gears to new ones, the new test gears should be fixed to gear shafts at such a relative rotational angle that a pair of new test gears mesh with each other with no resistance. Incidentally, when two gears are meshing with each other without resistance, it is defined herein that there is no rotation phase difference between the two gears. Here, the term "without resistance" means that the meshing of the two gears is in an optimum state.
The meshing of the two gears without resistance would not easily be achieved by adjusting key positions for fixing the test gears to the gear shafts. Accordingly, couplings of the gear shafts are in fact adjusted for achieving no rotation phase difference between a pair of test gears. This not only lengthens the test start-up time, but also makes it difficult to improve the test accuracy and reliability.